Mycotoxicosis in Pigs: Moldy Feed Poisoning and Key Warning Signs

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Quick Answer
  • Mycotoxicosis means illness caused by toxins made by molds growing in feed or grain. Pigs are especially sensitive to several mycotoxins, including deoxynivalenol (vomitoxin), zearalenone, aflatoxins, fumonisins, and ochratoxin.
  • Common warning signs include sudden feed refusal, vomiting, poor growth, diarrhea, breathing trouble, weakness, and reproductive changes such as swollen vulvas, infertility, or false heat.
  • See your vet promptly if more than one pig is affected, if feed recently changed, or if pigs have breathing distress, collapse, severe dehydration, or sudden deaths.
  • Early care usually focuses on removing the suspected feed, supportive treatment, and testing feed or tissues to identify the toxin and guide herd-level decisions.
Estimated cost: $150–$2,500

What Is Mycotoxicosis in Pigs?

Mycotoxicosis is poisoning caused by mycotoxins, which are toxic compounds produced by certain molds in grain, pellets, and stored feed. The feed may look obviously moldy, but not always. In some cases, the mold is no longer visible while the toxin is still present, so pigs can become sick even when the ration does not look dramatically spoiled.

Pigs are one of the more sensitive livestock species for several important mycotoxins. Different toxins affect different body systems. Deoxynivalenol (DON, or vomitoxin) often causes feed refusal and vomiting. Zearalenone acts like estrogen and can trigger vulvar swelling, fertility problems, and pseudopregnancy. Fumonisins can cause severe lung injury and sudden death in swine. Aflatoxins and ochratoxin are more likely to damage the liver, kidneys, immune system, or growth.

Because signs can overlap with infections, poor nutrition, or management problems, mycotoxicosis is often a herd-level puzzle rather than a single-pig diagnosis. Your vet will usually look at the pattern of illness, recent feed history, age group affected, and lab testing before deciding how likely mold toxins are in your pigs.

Symptoms of Mycotoxicosis in Pigs

  • Feed refusal or sudden drop in appetite
  • Vomiting or retching after eating
  • Poor weight gain or weight loss
  • Diarrhea or loose manure
  • Lethargy, weakness, or rough hair coat
  • Coughing, open-mouth breathing, or sudden breathing distress
  • Swollen vulva in gilts, enlarged teats, infertility, or irregular heats
  • Abortions, early embryo loss, or pseudopregnancy in breeding pigs
  • Jaundice, bleeding tendency, or severe depression
  • Sudden death, especially in growing pigs on corn-based feed

When mycotoxins are involved, several pigs in the same group often show similar signs within days to weeks of a new batch of feed or a storage problem. Mild cases may look like poor thrift, reduced feed intake, or slower growth. More severe cases can involve vomiting, dehydration, reproductive problems, or breathing distress.

See your vet immediately if pigs are struggling to breathe, collapsing, unable to stand, severely dehydrated, or dying suddenly. Those signs can occur with fumonisin exposure and other emergencies, so fast veterinary guidance matters.

What Causes Mycotoxicosis in Pigs?

Mycotoxicosis happens when pigs eat feed contaminated with toxins from molds such as Fusarium, Aspergillus, or Penicillium. These molds may grow in the field before harvest or later during storage if grain stays too wet, damaged, poorly aerated, or warm. Corn and cereal grains are common sources, but pelleted feeds, screenings, and mixed rations can also be involved.

Several toxins matter in pigs. DON (vomitoxin) is strongly linked with feed refusal and vomiting. Zearalenone is especially important in gilts and sows because it can mimic estrogen and disrupt reproduction. Fumonisins are associated with lung injury and can cause rapid decline or sudden death. Aflatoxins can damage the liver and suppress immunity, while ochratoxin is more closely tied to kidney injury.

Risk rises when feed contains broken kernels, has been stored in damp bins, has caked or heated, or has a musty odor. One more challenge is that feeds may contain more than one mycotoxin at the same time. That can make signs less predictable and sometimes more severe than a single toxin alone.

How Is Mycotoxicosis in Pigs Diagnosed?

Diagnosis usually starts with a careful history. Your vet will ask when signs began, which pigs are affected, whether a new feed delivery or grain source was introduced, and whether the ration smells musty, looks dusty, or contains fines and broken kernels. The pattern matters. For example, feed refusal and vomiting may point toward DON, while vulvar swelling in young gilts raises concern for zearalenone.

A physical exam and basic lab work can help assess dehydration, organ injury, and competing problems. Depending on the case, your vet may recommend bloodwork, necropsy of pigs that died, and histopathology of liver, lung, or kidney tissue. These tests do not always prove a specific toxin, but they can support the diagnosis and rule out infectious disease.

Feed testing is often the most useful next step. Your vet may submit representative samples of the suspect ration, grain, or bin screenings for a mycotoxin panel. Sampling technique matters because toxins are not evenly distributed in feed. In many cases, diagnosis is based on the combination of herd history, compatible signs, feed analysis, and improvement after the contaminated feed is removed.

Treatment Options for Mycotoxicosis in Pigs

Spectrum of Care means you have options. Here are treatment tiers at different price points.

Budget-Conscious Care

$150–$600
Best for: Mild to moderate cases where pigs are stable and the main goal is to stop exposure quickly while keeping costs controlled
  • Prompt call to your vet for herd-level guidance
  • Immediate removal of suspected feed and replacement with clean feed
  • Basic on-farm exam or farm-call assessment
  • Supportive care such as fresh water access, electrolyte support, and close monitoring
  • Targeted submission of one feed sample for mycotoxin screening when available
Expected outcome: Often fair to good if the toxin source is removed early and pigs have not developed major lung, liver, kidney, or reproductive injury.
Consider: Lower upfront cost, but less diagnostic detail. This approach may miss mixed toxins, secondary disease, or the full herd impact if signs are severe or prolonged.
Most Common

Recommended Standard Treatment

$600–$1,500
Best for: Most pigs and small herd outbreaks where confirmation and practical management changes are both important
  • Farm visit with full veterinary exam and ration review
  • Removal of suspect feed plus transition plan to safer feed
  • Bloodwork or selected diagnostics to assess dehydration and organ injury
  • Feed testing through a veterinary or agricultural diagnostic lab
  • Supportive treatment directed by your vet, which may include fluids, nutritional support, and treatment of secondary complications
  • Short-term herd monitoring plan for growth, reproduction, and additional cases
Expected outcome: Good in many DON or zearalenone cases once exposure stops, but more guarded when pigs have severe respiratory signs, marked liver damage, kidney injury, or reproductive losses.
Consider: More complete and more actionable than conservative care, but costs rise with farm-call time, lab work, and the number of pigs evaluated.

Advanced / Critical Care

$1,500–$2,500
Best for: Breeding herds, valuable pigs, sudden-death events, severe respiratory disease, or cases where multiple toxins or major production losses are suspected
  • Urgent veterinary assessment for severely affected pigs
  • Expanded diagnostics such as CBC, chemistry, necropsy, histopathology, and broader feed or tissue testing
  • Intensive supportive care for valuable or critically ill pigs, including IV or repeated fluid therapy when feasible
  • Detailed herd investigation of storage, sourcing, and feed handling
  • Consultation on longer-term ration reformulation, toxin-risk reduction, and reproductive follow-up
Expected outcome: Variable. Some pigs recover well after exposure ends, but prognosis is guarded to poor for pigs with fulminant pulmonary edema, severe organ failure, or major reproductive damage.
Consider: Provides the most information and support, but requires higher spending and may still not reverse damage that has already occurred.

Cost estimates as of 2026-03. Actual costs vary by location, clinic, and individual case.

Questions to Ask Your Vet About Mycotoxicosis in Pigs

Bring these questions to your vet appointment to get the most out of your visit.

  1. Which mycotoxins best fit my pigs' signs and age group?
  2. Should I stop this feed immediately, and what should I feed instead while we wait for results?
  3. Which pigs need to be examined first or treated most urgently?
  4. Do you recommend feed testing, tissue testing, or both in this case?
  5. How should I collect a representative feed sample from bins, bags, or feeders?
  6. Are reproductive problems in my gilts or sows likely related to zearalenone exposure?
  7. What signs would mean this has become an emergency, especially for breathing problems or sudden deaths?
  8. What storage or feed-handling changes would most reduce the risk of this happening again?

How to Prevent Mycotoxicosis in Pigs

Prevention starts with feed quality. Buy grain and complete feed from reputable suppliers, rotate inventory, and avoid feeding material that is caked, damp, musty, overheated, or visibly moldy. Clean bins, augers, and feeders regularly so old fines and spoiled feed do not contaminate fresh batches.

Storage matters as much as sourcing. Keep grain dry, improve ventilation, repair leaks, and watch for condensation in bins. Broken kernels and screenings often carry more toxin than intact grain, so cleaning grain can reduce risk. If a crop year or region has known mold pressure, ask your feed supplier or your vet whether screening or routine testing makes sense for your herd.

If pigs develop unexplained feed refusal, vomiting, fertility changes, or sudden breathing problems, save a sample of the suspect feed before discarding it and contact your vet. Early removal of contaminated feed can limit losses. Some feed additives are marketed to reduce toxin effects, but they do not replace good storage, careful sourcing, and veterinary guidance.

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